Duct support structure



FIG. 1 is a left side perspective of a duct support structure of theclaimed design;

FIG. 2 is a right side view of the duct support structure of the claimeddesign;

FIG. 3 is a front view of the duct support structure of the claimeddesign;

FIG. 4 is a back view of the duct support structure of the claimeddesign;

FIG. 5 is a top view of the duct support structure of the claimeddesign; and,

FIG. 6 is a bottom view of the duct support structure of the claimeddesign.

CLAIM The ornamental design for a duct support structure, as shown anddescribed.